1. Field of the Invention
The present invention relates to an imaging apparatus, such as a digital camera, and a technology related thereto.
2. Description of the Related Art
In an imaging apparatus, photometry using a photometric sensor and distance measurement using a phase difference-based AF sensor are carried out with, in general, a diaphragm in an imaging lens fully open. An AF lens is then driven based on the result of the distance measurement (measured distance) to carry out automatic focusing (AF). When a release button is fully pressed to issue an imaging instruction, the diaphragm (when described in detail, diaphragm blades) is driven from its fully open state to a state corresponding to a diaphragm aperture for imaging, and automatic exposure (AE) is carried out. The diaphragm aperture for imaging is determined based on the result of the photometry (measured photometric value). A shutter is then fully opened for a predetermined exposure period, and an image of a subject is captured. Thereafter, the diaphragm temporarily returns to its open fully state to carry out the distance measurement and photometry for the next image to be captured. The series of operations described above is repeated to acquire a plurality of captured images successively.
The same operations are carried out in continuous imaging as well. For example, after a first captured image is acquired, the diaphragm (when described in detail, diaphragm blades) temporarily returns from the state for imaging (the state corresponding to a diaphragm aperture for imaging) to the fully open state, and the distance measurement and photometry are carried out for the next captured image acquisition. The diaphragm is then transits again from the fully open state to the imaging state, and a second captured image is acquired. Continuous imaging is carried out by repeating the series of operations described above.
In the procedure described above, the imaging intervals between a plurality of captured images acquired in the continuous imaging are preferably small. That is, the continuous imaging speed is preferably fast.
JP-A-2006-215399, for example, describes a technique for improving the continuous imaging speed.
According to the technique described in JP-A-2006-215399, the period necessary to open or close a diaphragm can be shortened by adjusting the timing at which the diaphragm driving operation is initiated. Specifically, JP-A-2006-215399 describes a technique for reducing a period corresponding to a driving period for an entrance zone in a diaphragm mechanism and an initial current conduction period.